Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 220929

Area Forecast Discussion
National Weather Service Buffalo NY
529 AM EDT Sat Oct 22 2016

Rain will continue to taper off across Western New York this way to cloudy skies and areas of drizzle, while
showers will linger across the Eastern Lake Ontario region through
tonight. Precipitation may change over to snow across the highest
elevations east of Lake Ontario tonight...with a coating of wet snow
possible across the top of the Tug Hill Plateau. Things will dry out
Sunday before another disturbance brings a chance of showers Sunday
night.  Otherwise, cool northwesterly flow will keep temperatures
below average into the middle of the week, with a chance of lake
effect rain showers southeast of the lakes.


The steady rain of the last 24 hours is finally beginning to taper
off across Western New York as the main deformation zone has shifted
into eastern New York and the elongated upper level low has moved
overhead. However, with much of the forecast area now under cool
northerly low level flow off of the lakes and plenty of wrap-around
moisture still lingering, we are still seeing areas of light
rainfall across western New York.

Expect this area of precip to continue to gradually shift to the
east through the rest of tonight and during the day on Saturday.
With winds shifting to the northwest and 850 mb temps falling below
0C, expect lake enhancement to prolong steadier precipitation
southeast of Lake Ontario, from Wayne County eastwards, with light
rain tied to the deformation zone persisting across the North
Country as well. To the west, this same cool northwesterly flow and
lingering low level moisture will also generate a response off the
lakes, however with a shorter fetch to work with and very dry air
above 850mb, this response will be mainly in the form of lingering
cloud cover throughout the day, along with areas of drizzle.

The cold air advection, along with a sharpening pressure gradient
between high pressure over the central Great Lakes and deepening low
pressure along the New England coast will result in increasingly
breezy conditions Saturday, with winds gusting up to 35 mph...
particularly near Lake Ontario and across higher elevations. The
abundant cloud cover, coupled with weak cold advection, means that
temperatures will climb little from morning lows around 40. Expect
temperatures to only top out in the low to mid 40s.

Showers will continue into tonight across the eastern Lake Ontario
region as the wrap-around moisture on the western flank of the
departing low pressure system continues to slide across the area.
With temperatures across inland portions of the North Country
falling into the low to mid 30s, we may see precip change over to
snow across the higher elevations of the area, with an accumulation
of up to an inch possible across the highest portions of the Tug and
the Western Adirondacks overnight. Otherwise, expect plenty of lake-
effect cloudiness to persist elsewhere, though any precip will still
be limited to patchy drizzle, as the bulk of the moisture will be
confined to the lowest 5000ft of the atmosphere, with a strong
subsidence inversion above that level. Temperatures will fall into
the upper 30s in the Southern Tier, with lower 40s near the
lakes...though continued breezy west-northwest flow will still make
it feel quite raw.


A persistent cool northwest flow will occur across the eastern Great
Lakes through this period as an anomalously deep surface low
wobbles over eastern Quebec and a western Canadian sourced high
pressure builds southeast across the Northern Plains, western Great
Lakes and Midwest states. This flow will largely feature dry
continental air especially when compared to our recent extended
period of rainfall but models do show at least two plumes of
moisture working through the flow tied to separate shortwave
troughs. These shortwaves will be the focus for driving any
showers and associated lake effect through early next week.

Much of Sunday will feature dry weather with only a slight chance of
some sprinkles southeast of the lakes as moisture and synoptic lift
being to increase ahead of the first shortwave trough. This
shortwave is forecast to shift just to our southwest across Lake
Erie into PA Sunday night but models are showing a brief shot of
moisture extending northeast across much of our CWA. Have featured
chance POPs across the large majority of the CWA with likely POPs
focused over the western Southern Tier. Temperatures should remain
warm enough for p-type to be rain showers but there is a slight
chance that if the eastern extent reaches the Tug Hill and western
ADKs that some wet snow could mix in.

In the wake of this shortwave look for some dry time early Monday
before a shot of -3C to -6C air shifts over the Great Lakes. This
cooler air will drive up lake induced instability with Surface-850mb
delta Ts of around 20C eventually building Lake Induced Equilibrium
Levels up to around 20kft. A second weak shortwave and plume of
shallow moisture will shift over our area Monday night into Tuesday
morning. This should drive bands of lake effect showers southeast of
the lakes with the highest chance POPs coming between about Midnight
and Noon Tuesday. A 310-320 flow will keep most of the Lake Effect
showers limited to the southern shore of Lake Ontario into the
northern Finger Lakes off Lake Ontario and across Chautauqua county
off Lake Erie. Temps in the 40s by day will equate ptype to rain
showers but some wet snow could mix in across the higher terrain
Monday night as temps fall into the upper to mid 30s. The Canadian
sourced surface high over the midwest region Tuesday will build east
toward our region Tuesday night. This will drive down a capping
inversion bringing an end to Lake Effect overnight.


High pressure centered over Canada will extend southeast across the
Lower Great Lakes Wednesday and Wednesday night. This will support
mainly fair dry weather with temperatures within a few degrees of
normal. Meanwhile...a Pacific shortwave crossing the Rockies will
start the process of cyclogenesis over the Central Plains.

The forecast become very unclear for Thursday and Thursday night as
00z model guidance shows a large divergence of solutions between the
EC and GFS/CMC. The EC is an outlier tracking the Central Plains
surface low across the Great Lakes into southeast Ontario while the
GFS/CMC both show the low weakening/dissipating over the lower
Ohio/mid Mississippi river valleys. Due to this large spread in
forecast guidance have leaned heavily on the SuperBlend which
actually favors the EC solution. This puts chance POPs in play for
Thursday into Friday. Temperatures both Thursday and Friday should
top out in the low to mid 50s.


Cold air advection on northwesterly flow will continue to generate
MVFR cigs across the forecast area through Saturday, with IFR
conditions likely to persist across the higher terrain of the
Southern Tier and North Country. Expect gradual improvement across
Western New York after 20Z-00Z, as deeper low level moisture begins
to shift away to the east. Lingering rain showers may change over to
snow showers later tonight across the higher elevations of the Tug
Hill Plateau and Western Adirondacks.


Sunday...MVFR/VFR. A chance for rain showers SE of the lakes.
Monday...Mainly VFR.
Tuesday...Mainly VFR.


A surface low centered north of Cape Cod will deepen as it moves
north across Maine and into Quebec through tonight. The tightening
gradient between this low and a narrow ridge of high pressure
moving into the central Great Lakes coupled with increasing cold air
advection will allow northwesterly winds to freshen to gale force
tonight across central Lake Ontario, and appropriate warnings have
been issued. Elsewhere, the brisk northwesterly flow will keep small
craft advisories in play well into Tuesday before high pressure
moves overhead Tuesday night into Wednesday.



The recent heavy rains have made a noticeable impact on area
rivers and streams, however given the antecedent drought
conditions, streams have had no flooding issues. The Allegany
River at Olean is currently cresting near action stage, while the
Black River will also be approaching action stage over the next 24
to 48 hours. However, with the bulk of the precipitation already
tapering off, no flooding issues are expected across the forecast


MARINE...Small Craft Advisory until 2 AM EDT Monday for LEZ041.
         Small Craft Advisory until 3 PM EDT Sunday for LEZ040.
         Small Craft Advisory until 8 PM EDT this evening for
         Gale Warning from 10 PM this evening to 11 AM EDT Sunday
         for LOZ062>064.
         Small Craft Advisory until 2 AM EDT Sunday for LOZ043-044.
         Gale Warning from 2 AM to 11 AM EDT Sunday for LOZ043-044.
         Small Craft Advisory until 11 PM EDT Sunday for LOZ042-045.



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